In a coronary intervention (PCI) which is a treatment to be carried out for myocardial infraction or angina pectoris, a treatment is carried out such that a catheter equipped with a guide wire therein is inserted from a base of a thigh, etc., into a blood vessel so that the catheter is reached the coronary artery of the heart via the blood vessel. As the device for the coronary intervention treatment, a stent is used. This stent is a medical device made of metal, such as a stainless-steel, and is used to improve treatment effects of a catheter treatment by staying at a stenosis part of a coronary artery expanded using a balloon and holding the blood vessel from the inner cavity. In this case, for example, in cases where a slight gap is generated between a previously arranged stent and a newly arranged stent, there is a possibility that the gap causes angiostenosis. Therefore, an accurate recognition of the stent position may be an important element in a coronary intervention treatment (see, for example, Patent Document 1).
According to a conventional configuration, radiation photographic images (e.g., frames) that form live images are superimposed with reference to a stent marker, so that an image in which the stent and vicinity thereof has become clear is generated. In this image, the stent of the subject and vicinity thereof appear clearer than each frame.
The generation method of this composite image will be specifically explained. Each frame configuring a live image is subjected to an image analysis, so that the position of the stent marker in each frame is specified. Then, each frame is subjected to movement processing and rotation processing so that stent markers that appear in each frame come to the same position. Frames in which the position and the inclination are adjusted with reference to the stent markers are superimposed to thereby generate a superimposed frame. In this superimposed frame, the stent which became clearer by being superimposed on each frame appears. Since this superimposed frame is enlarged for the purpose of obtaining better visibility, it may be required to perform a trimming processing on the superimposed frame before displaying the superimposed frame on a monitor. For example, a part of the superimposed frame in which the stent appear is trimmed, so that a trimming frame is generated. This trimming frame includes an image in which the stent appeared small in the superimposed frame was taken out of the superimposed frame and displayed in an enlarged manner.
It is configured such that this trimming frame is sequentially updated during imaging of the live image and that the monitor displaying the trimming frame always displays the updated trimming frame. Therefore, the monitor displays this trimming frame as a frame configuring a moving image. This moving image of the trimming frame is a moving image chasing the clearly enlarged stent appearing small in the live image with time.